Biocidal Polymers Research Articles

Biocidal polymer coatings based on porphyrin-modified epoxy-amine networks

For the first time, a pronounced biocidal activity of modified polymers with a porphyrin content of 21.4 μM (0.002 wt%) against Staphylococcus aureus was demonstrated. In order to develop new biocidal polymer coatings, a study was carried out on diglycidyl ether of bisphenol A (DGEBA) and porphyrin-modified oligomeric diamine systems. The study investigated the solubility of porphyrins in oligomers through experimental and theoretical means, using Van Krevelen's approach of additive group contributions. Fully cured epoxy-amine polymer materials modified with varied free-base tetraarylporphyrins were obtained. The materials were studied by means of thermogravimetry, differential scanning calorimetry, UV–Vis and fluorescence spectroscopy. The proposed approach to the formation of modified epoxy-amine materials allows preservation of the photophysical properties of porphyrins, including their photostability. The addition of modifiers in 4.28–21.4 μM range of concentrations makes it possible to keep the thermophysical and thermochemical properties of the polymer matrix.

Biocidal polymer derived near white light-emitting polymeric carbon particles for antibacterial and bioimaging applications.

A growing antimicrobial crisis has increased demand for antimicrobial materials. It has become increasingly popular to convert polymeric macromolecules into polymeric carbon particles (PCP) in order to achieve highly biocompatible materials with unique properties as a result of the ability to synthesize nanomaterials of the right size and add value to existing stable polymers. This work presents the tuning of PCP for antibacterial application by combining a biocidal polymer with one-pot solvothermal synthesis. PCP displayed broad-spectrum antibacterial activity via various mechanisms, including inhibition of bacterial cell walls, ROS generation, and antibiotic resistance. Furthermore, these biocidal PCP were observed to show excitation-independent near-white light emission which on the other hand is generally possible due to mixed sizes, doping, and surface effects. As opposed to the parent biocidal polymer, PCP added ROS-mediated bactericidal activity, increased cytocompatibility, and nanofibers with anti-adhesive effects and potential of imaging bacterial cells.

The transformation of cellulose acetate into a new biocidal polymer by effluent-free grafting in supercritical carbon dioxide

The study reports an effluent-free, green process for the production of materials with favorable antibiofilm properties by cellulose acetate grafting with quaternary ammonium compounds in supercritical carbon dioxide. Two quaternary ammonium compounds, N-(2-Hydroxyethyl)-N,N-dimethylundecan-1-aminium Bromide and N-(11-Hydroxyundecanyl-N,N-dimethyltetradecan- 1-aminium Bromide, were synthesized and chemically attached to cellulose acetate via hexamethylene diisocyanate as a linker under the conditions of 30 MPa and 70 °C. The polymer modification occurred in its whole volume. The chemical conversion led to a decrease in the degree of crystallinity and the appearance of a rugged polymer surface. However, the cross-section imaging of the newly obtained materials revealed a compact polymer structure. The functionalized materials acquired hydrophobic properties. Microbiological tests showed the impossibility of Staphylococcus aureus ATCC 29213, Methicillin-resistant Staphylococcus aureus ATCC 43300, Escherichia coli ATCC 10536, and Salmonella Enteritidis ATCC 13076 attachment to the material obtained by the cellulose acetate grafting procedure with N-(11-Hydroxyundecanyl-N,N-dimethyltetradecan- 1-aminium Bromide.

Impacts of non-microbial soils on polychloramide disinfectants

The presence of some nonmicrobial chemicals and surfaces, herein called “soils”, are known to degrade the performance of biocides, and biocidal assays often include mixtures of materials to mimic the effects of soils. We hypothesized that water-soluble anionic polychloramide biocides were less sensitive to soil interference than cationic polymeric biocides. The relationships between soil composition and antimicrobial polymer biocidal activity were compared for an anionic polychloramide, a cationic polychloramide, and a cationic poly(quaternary ammonium) biocide. The nanoscale soil models individually investigated were polyacrylic acid (PAA), cellulose nanocrystals (CNCs), and bovine serum albumin. The low molecular weight model soils were ammonium chloride, glycine, and succinimide. Three types of soil impacts were identified: 1) sequestration, whereby the soil physically inhibited transport of the biocide to microbes; 2) extraction, whereby the soil reduced or extracted oxidative chlorine, decreasing or eliminating the oxidative chlorine strength; and 3) extraction whereby the biocidal activity increases in the presence of a low molecular weight chemical that carries oxidative Cl from the polymer to the microbes. PAA and CNCs inhibit cationic biocides by sequestration but have little impact on anionic polychloramide. Glycine and BSA extract oxidative chlorine, lowering the biocidal activity of the anionic and cationic polychloramides while not impacting the poly(quaternary ammonium) biocide. Finally, the presence of succinimide increased bacteria deactivation of both anionic and cationic polychloramides. We propose that succinimide extracts oxidative chlorine from the polychloramides and transports it to the bacteria.

Bioactive surfaces with well-defined amphiphilic copolymers containing a natural terpene-based monomer

New amphiphilic cationic copolymers based on poly((methacryloyloxy) ethyl trimethylammonium chloride) (PMETAC) and bio-based poly(thymol methacrylate) (PTMA) were prepared by atom transfer radical polymerization (ATRP) methods, using low concentration of metal catalyst and a bio-based eutectic mixture (EM), composed of L-menthol and thymol. The antimicrobial activity of the polymers was evaluated against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) bacteria.The results in solution showed that increasing the terpenic segment (PTMA) in the copolymers resulted in lower antimicrobial activity against S. aureus (as the MIC increases from 3.1 to 100 μM) and higher activity against E. coli (as the MIC decreases from 400 to 200 μM).Scanning electron microscopy (SEM) analysis suggests that polymers affected the bacterial viability by damaging the cell structure. The synthesized biocidal polymers were used as additives in polyurethane-based varnish formulations to produce bioactive coated surfaces that were found to be more active against E. coli. Coatings containing either PTMA or PMETAC homopolymers were more efficient than those containing PMETAC-co-PTMA copolymers. A dramatic improvement in the antimicrobial activity of PMETAC-containing varnish against both S. aureus (3 orders of magnitude) and E. coli (4 orders of magnitude) was observed when an aqueous solution of the homopolymer was applied to the dried varnish instead of being incorporated into the varnish formulation. The strategy presented here is simple and opens the door for the preparation of customized bioactive surfaces to prevent bacterial infections.

Development of Environmentally Friendly Biocidal Coatings Based on Water-soluble Copolymers for Air-cleaning Filters.

Air pollution by pathogens has posed serious concern on global health during the last decades, especially since the breakout of the last pandemic. Therefore, advanced high-efficiency techniques for air purification are highly on demand. However, in air-filtering devices, the prevention of secondary pollution that may occur on the filters remains a challenge. Toward this goal, in the present work, we demonstrate a facile and eco-friendly process for the biocidal treatment of commercial high-efficiency particulate air filters. The antibacterial filters were successfully prepared through spray coating of aqueous solutions based on biocidal water-soluble polymers, poly(sodium 4-styrene sulfonate-co-cetyl trimethylammonium 4-styrene sulfonate-co-glycidyl methacrylate) [P(SSNa24-co-SSAmC1656-co-GMA20)] and poly(2-dimethylaminoethyl)methacrylate. Significantly, an optimized green route was developed for the synthesis of the used polymers in aqueous conditions and their stabilization through cross-linking reaction, leading to biocidal air filters with long-lasting activity. The developed coatings presented strong and rapid antibacterial activity against Staphylococcus aureus (in 5 min) and Escherichia coli (in 15 min). Moreover, the cytotoxicity test of the polymeric materials toward Α549 lung adenocarcinoma cells indicated very low toxicity as they did not affect either the cell growth or cell morphology. The above-mentioned results together with the scalable and easy-to-produce green methodology suggest that these materials can be promising candidates as filter coatings for use on air-purification devices.

EDNA Inactivation and Biofilm Inhibition by the PolymericBiocide Polyhexamethylene Guanidine Hydrochloride (PHMG-Cl).

The choice of effective biocides used for routine hospital practice should consider the role of disinfectants in the maintenance and development of local resistome and how they might affect antibiotic resistance gene transfer within the hospital microbial population. Currently, there is little understanding of how different biocides contribute to eDNA release that may contribute to gene transfer and subsequent environmental retention. Here, we investigated how different biocides affect the release of eDNA from mature biofilms of two opportunistic model strains Pseudomonas aeruginosa ATCC 27853 (PA) and Staphylococcus aureus ATCC 25923 (SA) and contribute to the hospital resistome in the form of surface and water contaminants and dust particles. The effect of four groups of biocides, alcohols, hydrogen peroxide, quaternary ammonium compounds, and the polymeric biocide polyhexamethylene guanidine hydrochloride (PHMG-Cl), was evaluated using PA and SA biofilms. Most biocides, except for PHMG-Cl and 70% ethanol, caused substantial eDNA release, and PHMG-Cl was found to block biofilm development when used at concentrations of 0.5% and 0.1%. This might be associated with the formation of DNA–PHMG-Cl complexes as PHMG-Cl is predicted to bind to AT base pairs by molecular docking assays. PHMG-Cl was found to bind high-molecular DNA and plasmid DNA and continued to inactivate DNA on surfaces even after 4 weeks. PHMG-Cl also effectively inactivated biofilm-associated antibiotic resistance gene eDNA released by a pan-drug-resistant Klebsiella strain, which demonstrates the potential of a polymeric biocide as a new surface-active agent to combat the spread of antibiotic resistance in hospital settings.

Biocidal Polymer Formulations and Coatings

Biocidal Polymer Formulations and Coatings

Recent Advances in the Development of Antimicrobial and Antifouling Biocompatible Materials for Dental Applications.

The risk of secondary bacterial infections resulting from dental procedures has driven the design of antimicrobial and antifouling dental materials to curb pathogenic microbial growth, biofilm formation and subsequent oral and dental diseases. Studies have investigated approaches based primarily on contact-killing or release-killing materials. These materials are designed for addition into dental resins, adhesives and fillings or as immobilized coatings on tooth surfaces, titanium implants and dental prosthetics. This review discusses the recent developments in the different classes of biomaterials for antimicrobial and antifouling dental applications: polymeric drug-releasing materials, polymeric and metallic nanoparticles, polymeric biocides and antimicrobial peptides. With modifications to improve cytotoxicity and mechanical properties, contact-killing and anti-adhesion materials show potential for incorporation into dental materials for long-term clinical use as opposed to short-lived antimicrobial release-based coatings. However, extended durations of biocompatibility testing, and adjustment of essential biomaterial features to enhance material longevity in the oral cavity require further investigations to confirm suitability and safety of these materials in the clinical setting. The continuous exposure of dental restorative and regenerative materials to pathogenic microbes necessitates the implementation of antimicrobial and antifouling materials to either replace antibiotics or improve its rational use, especially in the day and age of the ever-increasing problem of antimicrobial resistance.

New promising antimicrobial material based on thermoplastic polyurethane modified with polymeric biocide polyhexamethylene guanidine hydrochloride

New antimicrobial polymer composite based on commercial polyurethane (PU) Laripur®LPR9020 and polymeric biocide polyhexamethylene guanidine hydrochloride (PHMG-Cl) has been prepared by solvent casting method. Modified PU films containing from 1 to 4 wt% of PHMG-Cl were characterized in terms of mechanical, thermal and surface properties, biocide release behavior, as well as antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis) bacterial strains. The results of mechanical testing indicate that the introduction of PHMG-Cl did not cause noticeable changes in the tensile strength of PU films, but improved their elasticity by at least 20–30%. The surface of PU/PHMG-Cl films was found to possess significantly higher hydrophobicity than neat polymer that is manifested in sharply increased water contact angle value from 72° for neat PU to 95° for PU/PHMG-Cl (2%). According to thermogravimetric analysis data, PU/PHMG-Cl composites are thermally stable to at least 300 °C which indicate their availability for melt processing by common methods. The results of differential scanning calorimetry showed reduction of both glass transition and melting temperatures of PU by more than 7 °C when contained only 1% of PHMG-Cl.Gradual release of polymeric biocide from modified PU films into water has been detected spectrophotometrically. The total biocide release ratio was found to be in the range from 29% to 48% after 50 hours immersion, depending on its content in polymer composite. PU/PHMG-Cl films showed much lower leaching rate into physiological saline solution compared to pure water (from 10% to 21% after 50 hours), which may be caused by poor solubility of polymeric biocide in sodium chloride solutions.The study of antibacterial activity of modified PU films using both disc agar diffusion and contact methods indicate high efficacy against tested microorganisms when contained 3% of polymeric biocide. So, this approach, based on the modification of PU resin with polymeric biocide PHMG-Cl, has been discussed in terms of potential medical applications when biocide release system or contact active material are necessary.

Light-Activated Antimicrobial Surfaces Using Industrial Varnish Formulations to Mitigate the Incidence of Nosocomial Infections.

Evidence has shown that hospital surfaces are one of the major vehicles of nosocomial infections caused by drug-resistant pathogens. Smart surface coatings presenting multiple antimicrobial activity mechanisms have emerged as an advanced approach to safely prevent this type of infection. In this work, industrial waterborne polyurethane varnish formulations containing for the first time cationic polymeric biocides (SPBs) combined with photosensitizer curcumin were developed to afford contact-active and light-responsive antimicrobial surfaces. SPBs were prepared by atom transfer radical polymerization, which allows control over the polymer features that influence antimicrobial efficiency (e.g., molecular weight), while natural curcumin was employed to impart photodynamic activity to the surface. Antibacterial testing against Gram-negative Escherichia coli revealed that glass surfaces coated with the new formulations displayed photokilling effect under white-light (42 mW/cm2) irradiation within only 15 min of exposure. In addition, it was observed a combined antimicrobial effect between the two biocides (cationic SPB and curcumin), with a higher reduction in the number of viable bacteria observed for the surfaces containing cationic SPB/curcumin mixtures in comparison with the one obtained for surfaces only with polymer or without biocides. The waterborne industrial varnish formulations allowed the formation of homogeneous films without the need for addition of a coalescing agent, which can be potentially applied in diverse surface substrates to reduce bacterial transmission infections in healthcare environments.

Biocidal Polymers: Synthesis, Characterization and Antimicrobial Activity of Bis-Quaternary Onium Salts of Poly(aspartate-co-succinimide)

Microbial multidrug resistance presents a real problem to human health. Therefore, water-soluble polymers based on poly(aspartate-co-succinimide) were synthesized via reaction of poly(aspartate-co-succinimide) with bis-quaternary ammonium or quaternary salts. The resultant copolymers were characterized by various techniques such as FTIR, TGA, 1HNMR, 13CNMR and elemental microanalysis. Antimicrobial activities of the new onium salts were investigated against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella typhi, and the fungi; Candida albicans, Aspergillus niger, Cryptococcus neoformans and Aspergillus flavus by agar diffusion method. Antimicrobial activity was studied in terms of inhibition zone diameters, in addition to the estimation of minimal inhibitory concentration (MIC) of the prepared compounds. A. niger and E. coli were the most affected microorganisms among the tested microorganisms with an inhibition zone of 19–21 (mm) in case of biocides, (V) and (VII). The obtained results showed that the quaternary onium salts have higher activity compared to the aspartate copolymer with MIC concentrations of 25 mg/mL for (VII) and (V) and 50 mg/mL for (VI) and (IV).

Enhanced Light‐Driven Antimicrobial Activity of Cationic Poly(oxanorbornene)s by Phthalocyanine Incorporation into Polymer as Pendants

AbstractAmphiphilic poly(oxanorbornene)s are promising synthetic polymers that mimic the structural properties and antimicrobial functions of naturally occurring antimicrobial peptides. Here, poly(oxanorbornene)s bearing pendant zinc(II) phthalocyanine and triphenyl(ethyl) phosphonium functionalities are synthesized by ring‐opening metathesis polymerization (ROMP). Fluorescence, singlet oxygen and triplet quantum yields of polymers are measured in dimethyl sulfoxide and aqueous medium. The singlet oxygen quantum yields of copolymers with the highest triphenyl and triethyl phosphonium content are found to be 0.29 and 0.41, respectively. Then, antimicrobial activities of polymers against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are investigated under both dark and light conditions. Synergistic effect of zinc(II) phthalocyanine and phosphonium‐containing poly(oxanorbornene) is observed that the conjugate possessing the most triphenyl phosphonium side chains has the highest activity under light against both gram‐positive and gram‐negative bacterial strains after 80 min irradiation, reducing the survival of E. coli or S. aureus by 99.9999%. Hemolytic concentrations of the copolymers are found between 8 and 512 µg mL−1. Scanning electron microscopy (SEM) proves that the bacteria membrane deforms after contacting with the biocidal polymer.

Effect of polymeric biocide polyhexamethylene guanidine hydrochloride on morpho-physiological and biochemical parameters of wheat seedlings under copper stress

Aim. To study the effect of polymeric biocide polyhexamethylene guanidine hydrochloride (PHMG-Cl) on morphophysiological and biochemical parameters of wheat seedlings in the presence of toxic concentration of copper ions. Methods. The growth-stimulating activity of PHMG-Cl in pure state, as well as in the presence of elevated concentrations of copper ions was studied by phytotesting method using wheat seed as a test culture. Physico-chemical interaction between PHMG-Cl and CuSO4 in water solutions was studied by spectrophotometry. Results. Wheat seed treatment with water solutions of polymeric biocide PHMG-Cl in the concentration range of 0.01–0.1 % causes an increase in the length of roots and shoots by over 50 % after 7 days of incubation. The concentration of PHMG-Cl of 1 % was found to have a depressive effect on growth characteristics of the tested plants. This fact indicates that the phytotoxicity of PHMG-Cl is at least two orders of magnitude lower compared with a common pesticide copper sulfate. Thus, wheat seed soaking in 200 μM (0.003 %) water solution of copper sulfate causes reduced length of shoots and roots (by 65 and 34 %, respectively), as well as reduced weight of shoots (by 20 %) and roots (by 74 %) The analysis of green mass showed signifi cantly reduced content of carotenoids (by 26 %) and water soluble fl avonoids (by 37 %), as well as chlorophyll a/b ratio (by 18 %) that indicates decreased plant metabolic activity. However, the toxic effect of copper sulfate ions signifi cantly diminished in the presence of PHMG-Cl (0.01 %). Thus, the length of shoots and roots was found to increase by 24 and 64 %, respectively, compared to the samples treated with CuSO4. Moreover, the content of pigments and fl avonoids in the green mass of seedlings reached the level of control samples. The results of spectrophotometric studies indicate the absence of physico-chemical interaction between PHMG-Cl and copper sulfate in water solutions. Conclusions. The polymeric biocide PHMG-Cl effectively stimulates growth and development of wheat seedlings in the concentration range of its water solutions of 0.01–0.1 %. In the presence of toxic copper sulfate concentration, PHMG-Cl does not possess the growth stimulating activity. However, the polymeric biocide signifi cantly improves copper stress resistance of plants, and normalizes their morpho-physiological indicators, photosynthetic characteristics and secondary exchange.

Amphiphilic water soluble cationic ring opening metathesis copolymer as an antibacterial agent

AbstractBacterial infection is a global problem, especially resistance acquired by bacteria against to antibiotics; there is urgent need for the development of antibiotics. Here, we proposed dendron‐grafted polymers via ring opening metathesis polymerization (ROMP) featuring different with tailored hydrophobicity/hydrophilicity and cationic charges. Dendritic oxanorbornene derivatives were synthesized having two and six carbon linkers and their corresponding random and block copolymers were prepared having pendant pyridinium salt moieties via ROMP. In total, 12 different water‐soluble dendronized cationic polymers featuring hexyl pyridinium moieties were prepared and investigated. Six carbon linker possessing triple charge density and hexyl pyridinium functionality each repeating unit copolymers exhibited high antibacterial activity against Gram‐positive bacteria (S. aureus). However, all the polymers were inactive against Gram‐negative bacteria (E. coli). Most of the copolymers are non‐hemolytic (>HC 50 = 1,000 μg/ml). It was also observed that, there is no significant effect between block copolymers and random copolymers keeping hydrophobicity and cationic charge density constant. Zeta potential was measured to investigate the mechanism in solution via the interaction of polymers with S. aureus, while scanning electron microscope (SEM) measurements image confirms damage of the bacterial cell wall after implementation of biocidal polymer.

Design of pH-Responsive Dissociable Nanosystem Based on Carbon Dots with Enhanced Anti-biofilm Property and Excellent Biocompatibility.

Bacterial biofilm poses a serious threat to human health, leading to increased and prolonged bacterial infections. How to solve the problem of eliminating biofilms effectively and rapidly while being nontoxic to normal cells is still a challenge. Here, we design a pH-sensitive anti-biofilm nanosystem formed by self-assembly between negatively charged carboxyl groups of poly(ethylene glycol_-COOH-polyethylenimine-2,3-dimethylmaleic anhydride (PPD) and positively charged amines on the surface of carbon dots derived from the ashes of calcined l-lysine powder (CDLys) (PPD@CDLys for short). The outmost copolymer could make PPD@CDLys facilely diffuse into the dense biofilm and reverse to be positively charged via hydrolysis, which lead to the acid-triggered disassembly of the nanosystem. After hydrolyzation, PPD would turn into a biocidal cationic polymer, which is prone to attaching on bacteria inside the biofilm and efficiently killing them. In addition, the released CDLys could induce intracellular reactive oxygen species (ROS) across the whole biofilm to degrade the matrix of extracellular polymer substances and kill resident bacteria deep into the biofilm. Finally, the prepared nanosystem effectively inhibits the formation of Staphylococcus aureus biofilm and rapidly destroys the mature biofilm by the synergy antibacterial effects of the cation and ROS. We also evaluate the biocompatibility of the nanocomposites. The results show that PPD@CQDLys has no toxicity to L929 and 3T3 cells and exhibits a zero hemolytic rate even when the concentration is up to 2000 μg/mL. The outstanding biocompatibility coupled with rapid anti-biofilm ability of the nanosystem presents an opportunity for it to be utilized as an effective pH-responsive and targetable anti-biofilm agent for controlling bacterial infections.

Fungicidal and bactericidal activity of alkyl-substituting polyetherguanidines

Background . Polyhexamethylene guanidines are widely used as biocides and disinfectants due to the wide range of their antimicrobial activity against Gram-positive and Gram-negative bacteria, viruses, fungi, and molds. The mechanism of biocidal action of polyguanidines is similar to that of quaternary ammonium compounds and has a membrane toxic nature. The advantages of polyhexamethylguanidines salts include their moderate toxicity and a lack of cumulative action against living organisms. The convenience of such polymeric biocides lies in their high water solubility and in the absence of volatility, which allows disinfectant work to be carried out in the presence of people. It is known that the introduction of alkyl radicals into the polymer chain leads to an increase in the bactericidal and fungicidal action of the obtained compounds. In order to enhance these properties, it seems promising to obtain polyetherguanidines with alkyl radicals in their structure. The aim of this work was to study the fungicidal and bactericidal activity of synthesized alkyl-substituted polyetherguanidinium iodides against a number of bacteria and microscopic fungi. Methods. Bacteria were grown on the meat-peptone agar for 48 hours at 28±2 °C. Test cultures of micromycetes were cultured on agar beer wort (6 ° B), incubated for 14 days at 28±2 °C. Antimicrobial and fungicidal activities of the newly synthesized alkyl-sub­sti­tuting polyetherguanidines were determined by the standard disco-diffusion method. Results. The synthesis of polyetherguanidinium iodide is carried out in four stages. The first stage is the synthesis of a guanidine-containing oligoether with terminal guani­dine moieties by the reaction between aromatic oligoepoxide and guanidine. The second stage is the synthesis of polyetherguanidinium chloride by the reaction between guanidinium-containing oligoether with terminal guanidine fragments and oligooxyethylenediamine of different molecular weight. In the third stage, the obtained polyetherguanidinium chloride is converted from the salt form to the base form by the reaction with an equivalent amount of alkali in ethanol. In the fourth stage, the basic polyetherguanidine is reacted with methyl iodide at a molar ratio of polyetherguanidine: methyl iodide components of 1:2. The bactericidal and fungicidal activities of alkyl-containing polyetherguanidinium iodides against various heterotrophic bacteria and microscopic fungi has been shown. It was found that polyetherguanidinium iodides at a concentration of 1–3% inhibited the growth of Gram-negative ( Escherichia coli 475, Klebsiella pneumonia 479) and Gram-positive ( Staphylococcus aureus 451) bacteria. The obtained alkyl-containing polyetherguanidinium iodides at a concentration of 1% for 14 days showed fungicidal activity in almost all studied isolates. With an increasing length of the oligoethylene oxi­de component, the obtained polymers with n = 10 and 50 did not show a fungicidal effect against Aspergillus niger , and the polymer with n = 50 – against the micromycete Aspergillus versicolor. If we determine the fungicidal effect as a whole, the polymer with n = 6 had the highest activity against all studied isolates after 14 days, while the fungicidal effect of polymers with n = 10 and n = 50 tends to decrease. All synthesized alkyl-containing polyetherguanidinium iodides showed the highest activity against such microscopic fungi as Cladosporium cladosporioides , Acremonium strictum , Alternaria alternate , Cladosporium sphaerospermum , Paecilomyces variotii , Stachybotrys chartarum. Also noteworthy is the selective effect of the obtained polymers on individual isolates. Conclusions. The obtained polyetherguanidinium iodides of different molecular weight at a concentration of 1–3% showed bactericidal activity against Staphylococcus aureus 451 , Escherichia coli 475, Klebsiella pneumoniae 479 and fungicidal effect against all fungi studied by us and can be used as disinfectants for indoor treatment. Keywords : polyetherguanidinium iodides, antibactericidal activity, antifungal activity

Antioxidant activity of polymeric biocide polyhexamethylene guanidine hydrochloride

Cationic polymer polyhexamethylene guanidine hydrochloride (PHMG-Cl) is promising biocide that combines a broad spectrum of antimicrobial activity, mod-erate toxicity, as well as reasonable cost. It is widely used as an effective disinfect-ant in cooling systems, swimming pools, and hospitals, personal hygiene products, etc. Recently PHMG-Cl was found to have pronounced anti-inflammatory and wound healing properties and therefore may be used for the treatment of chronic wounds and thermal burns. This may indicate the antioxidant activity of polymeric biocide. In this study, PHMG-Cl has been synthesized by melt polycondensation of guanidine hydrochloride and 1,6-hexamethylenediamine. The structure of the cati-onic polymer was confirmed by 1H NMR and IR spectroscopy. The viscosity-average molecular weight of PHMG-Cl was found to be 10700. The antioxidant activity of PHMG-Cl has been studied by using different methods. In the methylene blue (MB) dye test, the oxidation of MB by hydroxyl radicals generating in Fenton’s system was found to decrease in the presence of PHMG-Cl in a molar ratio to MB of 5:1 and 10:1 (by 26 % and 38 %, respectively). At the same time, complete dye oxidation was observed when guanidine hydrochloride was used instead of PHMG-Cl. The antioxidant activity of PHMG-Cl has also been studied in the model system of radical chain oxidation of benzyl alcohol (BA). In this system, alkyl and peroxyl radicals are formed. The antioxidant activity was determined by a decrease of the initial rate of oxygen absorption during the initiated oxidation of BA. The introduc-tion of PHMG-Cl into the oxidized system in the concentrations ranged from 1.3·10-3 - 1.6·10-2 mol/l decreased the oxidation rate of BA by 4.5–88 %. This result demonstrates that PHMG-Cl effectively inhibits radical chain oxidation of BA. However, further research is needed to elucidate the mechanism of free radical de-activation by a polymer biocide.

Preparation and Characterization of PMMA-AgNPs Polymer Composite as a Dental Prosthesis

Silver nanoparticles (AgNPs) have been used for centuries in the field of medicine due to the antimicrobial properties. AgNPs has been synthesized and incorporated in different aspects of biomaterials. It is reported that AgNPs as a result of its small size, it provides sufficient antimicrobial effect at lower filler level, thus can be used in dentistry for prevention and reduction of biofilm formation on a surfaces of dental prosthesis. The purpose of this study is to develop AgNPs antimicrobial acrylic resin for dental prosthesis. The effect of AgNPs incorporated into acrylic resin poly methyl methacrylate (PMMA) on the bacterial biofilm was studied in terms of bacterial growth and the incorporating effect on the thermal stability of these polymeric biocides was evaluated. Silver nanoparticles in colloidal form was added to PMMA(ONDA-CRYL) using microwave and make four dental prosthesis at the different concentration. The specimens were delivered to the four toothless patients for 21 days. The formed biofilm was tested for microbiological study (taxonomic profile). After setting, the specimens were characterized to determine the spatial distribution of AgNPs on the PMMA matrix through scanning electron microscope and the thermal stability was examined using TGA and DSC. The modified PMMA prosthesis base containing AgNPs, which exhibited good in vivo antimicrobial properties without altering their thermal properties of degradation as well as their mechanical properties and minimize the maximum infectious signs by reducing the formation of microbial biofilm forming on the surfaces of dental prostheses. As the modification of PMMA with AgNPs improved the anti-biofilm properties without altering its mechanical and thermals properties to the degradation, it could be used as a dental prosthesis.

Inhibition of fungal growth by silicones modified with cationic biocides

Filamentous fungi are present everywhere in our environment and can grow on almost any substance in presence of moisture. Protecting the indoor environment against microbial growth remains a complex issue especially in sanitary applications or where protection against moulds is critical. Silicone samples containing 2% or 5% (w/w) of the cationic biocides polyhexamethylene guanidine dodecylbenzenesulfonate (PHMG-DBS), 1-octyl-3-methylimidazolium tetrafluoroborate (OMIM-BF4) or 1-dodecyl-3-methylimidazolium tetrafluoroborate (DMIM-BF4) were tested against a series of fungal species implicated in indoor fungal contamination. Our investigations were conducted according to the international standard ISO 16869 i.e. with a carbon-poor Nutrient-Salt-Agar (NSA) culture medium, and also with a carbon-rich Peptone-Dextrose-Agar (PDA) culture medium composed of pancreatic peptone, glucose and agar-agar as the spore suspension agar overlay. The experimental protocol using the PDA medium proved to be the most efficient procedure for discriminating, in a week only, the control analysis and those using modified silicones. Our results demonstrate that silicones containing 5% of polymeric biocide PHMG-DBS present higher antifungal activity on the filamentous fungi than long-chain imidazolium ionic liquids-containing silicones. The possible mechanisms of antifungal action of cationic biocides are discussed. The efficacy of PHMG-DBS demonstrates that such modified-silicones can prevent microbial growth and silicone deterioration by microorganisms in areas with high humidity levels such as kitchens and bathrooms as well as hospitals and microbiology laboratories.